2. Secretions

When you start to notice vaginal discharge, this is a sign you're at your most fertile. During this time you start to produce more estrogen, which results in mucus-like vaginal discharge.

3. Increased body temperature

When you have high levels of progesterone, your body temperature rises. To know when this is happening, take your temperature every day when you wake up in the morning. Keeping track will allow you to notice changes, even if they're minimal.

4. Pain

Many women have stomach pain during certain times of the month, and this pain is typically caused by ovulation. When you're ovulating and fertile, your ovaries can grow to the point of being painful in some cases.